Electroconductive device, organic electroluminescence device using the device and process for producing the electroconductive device

ABSTRACT

An electroconductive device is constituted by a pair of oppositely disposed electrodes, and a luminescence layer and an electroconductive layer disposed between the electrodes. The electroconductive layer includes a mixture of a plurality of organic compounds which are mutually structural isomers and include a major component and a minor component. The mixture contains the major and minor components in a (major component)/(minor component) ratio of 1/1 to 9.1. When the electroconductive layer is used as a carrier injection or transport layer, preferably an electron injection layer, a resultant electroluminescence (EL) device exhibits a high luminescence efficiency.

FIELD OF THE INVENTION AND RELATED ARAT

[0001] The present invention relates to an organic electroluminescence(EL) device for use in, e.g., flat panel displays, projection displays,and printers; an electroconductive device used for the EL device; and aprocess for producing the electroconductive device.

[0002] Since T. W. Tang et al substantiated in 1987 that it is possibleto effect high-brightness luminescence under application of a low DCvoltage by utilizing a lamination structure comprising a film offluorescent metal chelate complex and a diamine-based molecular film, anapplied study on an organic electroluminescence (EL) device as aluminescence device with high-speed responsiveness and high efficiencyhas been extensively conducted. The organic EL device is a self-lightemitting device of a carrier injection type using luminescence occurringat the time of re-combination of electrons and holes reached to aluminescent layer.

[0003]FIG. 6 shows a structure of an ordinary organic EL device.

[0004] Referring to FIG. 6, the EL device includes a transparentsubstrate 21, and thereon layers of a transparent electrode 22, a holetransporting layer 23, a luminescent layer 24 and a metal electrode 25are successively disposed in this order. Between the metal electrode 25(as a cathode) and the transparent electrode 22 (as an anode) for takingout emitted light, organic compound layers 20 comprising theluminescence layer 24 and the hole transporting layer 23 are formed anddisposed each in a thickness of ca. several hundred Å. Examples of thecathode metal electrode 25 may include a metal or an alloy having asmaller work function, such as aluminum, aluminum-lithium alloy andmagnesium-silver alloy. Examples of the anode transparent electrode 22may include an electroconductive material having a larger work function,such as ITO (indium tin oxide). The organic compound layer 20 in thisstructure (FIG. 6) has two-layer structure comprising the luminescencelayer 24 and the hole transporting layer 23.

[0005]FIG. 7 shows another structure of an ordinary organic EL device.

[0006] Referring to FIG. 7, the EL device includes a transparentsubstrate 21 on which a transparent electrode 22 (anode), a holetransporting layer 23, a luminescence layer 24, an electron transportinglayer 31 and a metal electrode 25 (cathode) are sequentially disposed inthis order. In this case, an organic compound layer 20 has a three-layerstructure comprising the hole transporting layer 23, the luminescencelayer 24 and the electron transporting layer 31.

[0007] Generally, the hole transporting layer (23 in FIGS. 6 and 7) hasa function of efficiently injecting holes from the anode (transparentelectrode 22) into the luminescence layer (24). On the other hand, theelectron transporting layer (31 in FIG. 7) generally has a function ofefficiently injecting electrons from the cathode (metal electrode 25)into the luminescence layer (24).

[0008] These hole transporting and electron transporting layers (23 and31) also have an electron (carrier) blocking function and a hole(carrier) blocking function, respectively, thus enhancing a resultantluminescence efficiency.

[0009] For these carrier (hole and electron) transporting layers (23 and31), it is important to exhibit a sufficient charge (carrier)transporting ability, particularly a carrier mobility.

[0010] Accordingly, if the carrier mobility in the carrier transportinglayer is increased, more carriers can be injected into the luminescencelayer 24 to enhance the luminescence efficiency. In addition, the highermobility is also effective in increasing a thickness (e.g., ca. 1 μm) ofthe carrier transporting layer (generally, several hundred Å-thick). Asa result, it becomes possible to prevent an occurrence of short circuitbetween the pair of electrodes (anode and cathode) and improve aproductivity.

[0011] For this reason, at present, a compound (material) for thecarrier transport layer has been extensively developed in order toachieve a high luminescence efficiency of the organic EL device.

[0012] In order to obtain a high electroconductivity by applying anelectric field to a pair of electrodes between which an organic compoundlayer is disposed, it is necessary to provide a good carrier(electron/hole) injection performance from the electrodes and a highcarrier mobility.

[0013] Incidentally, although hole injection/transport materialsexhibiting relatively good performances have been proposed, an electroninjection/transport material exhibiting a sufficient characteristic hasnot been found as yet.

SUMMARY OF THE INVENTION

[0014] In view of the above-mentioned problem, an object of the presentinvention is to provide an electroconductive device using a carrierinjection and/or transport layer comprising a material suitable forefficiently injecting and/or transporting carriers (holes or electrons).

[0015] Another object of the present invention is to provide an organicelectroluminescence (EL) device including the electroconductive deviceand having a high luminescence efficiency and a high reliability.

[0016] A further object of the present invention is to provide a processfor producing the electroconductive device.

[0017] According to the present invention, there is provided anelectroconductive device, comprising: a pair of oppositely disposedelectrodes, and a luminescence layer and an electroconductive layerdisposed between the electrodes, wherein

[0018] the electroconductive layer comprises a mixture of a plurality oforganic compounds which are mutually structural isomers and include amajor component and a minor component, the mixture comprising the majorand minor components in a (major component)/(minor component) ratio of1/1 to 9/1.

[0019] According to the present invention, there is also provided anelectroluminescence (EL) device including the above-mentionedelectroconductive device wherein the electroconductive layer is used asa carrier injection layer and/or a carrier transport layer.

[0020] According to the present invention, there is further provided aprocess for producing the above-mentioned electroconductive device,comprising:

[0021] a step of forming the above-mentioned electroconductive layerbetween the pair of electrodes.

[0022] These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a schematic sectional view of an embodiment of anelectroconductive device (organic EL device) prepared in Example 2(appearing hereinafter) according to the present invention.

[0024]FIGS. 2 and 3 are respectively a graph showing a current(density)-voltage characteristic of an organic EL device prepared inExample 2 (FIG. 2) and Comparative Example 1 (FIG. 3), respectively.

[0025]FIGS. 4 and 5 are respectively a graph showing a luminescenceefficiency of an organic EL device prepared in Example 2 (FIG. 4) andComparative Example 1 (FIG. 5), respectively.

[0026]FIGS. 6 and 7 are respectively a schematic sectional view of anembodiment of an organic EL device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The electroconductive device according to the present inventionis characterized in that an electroconductive layer disposed between apair of electrodes is formed by using a mixture of a plurality oforganic compounds which are mutually structural isomers and include amajor component and a minor component (hereinafter, referred to as a“structural isomer mixture”). The structural isomer mixture comprisesthe major and minor component in (major component)/(minor component)ratio of 1/1 to 9/1, preferably 1/1 to 5/1.

[0028] The organic EL device according to the present invention usingthe electroconductive layer as a carrier injection layer and/or acarrier transport layer, preferably as an electron injection layerand/or an electron transport layer.

[0029] Herein, the structural isomers refer to compounds having anidentical ring structure and an identical rational formula but having(molecular) structures different in the manner in which their atoms arelinked.

[0030] A compound molecule having at least one ring structure has aplanar molecular structure by nature, thus being liable to becrystallized in the case of a single compound (free from structuralisomer).

[0031] On the other hand, we have found that it is possible to stablyforming an amorphous structure by using an structural isomer mixture,particularly a mixture of low-molecular compounds each having such aring structure that a plurality of rings are connected via a singlebond.

[0032] In the present invention, by using the structural isomer mixturehaving such a stabilized amorphous structure, it becomes possible toform an electroconductive layer exhibiting a high carrier injectionand/or transport performance. Further, by using the electroconductivelayer as a charge injection and/or transport layer, it is possible toprovide an organic EL device with a high luminescence efficiency.

[0033] Incidentally, with respect to a luminescent layer, it has beensuggested that the luminescent layer containing an aminoquinolinecomplex having a facial-rich stereostructure provides betterperformances (Japanese Laid-Open Patent Application (JP-A) No. 4-85388).

[0034] According to the present invention, by using the structuralisomer mixture in the electroconductive layer (as the carrier injectionand/or transfer layer, the resultant EL device exhibits an excellentluminescent characteristic.

[0035] In the present invention, the organic compounds constituting thestructural isomer mixture may preferably be represented by the followingformula (1):

(R—X)_(n)—Ar—(X′—R′)_(m)  (1),

[0036] wherein Ar denotes a connected ring structure comprising twosingle rings connected with each other via a single bond or two fusedrings connected with each other via a single bond; X and X′independently denote a single bond, —O—, —S—, —OOC— or —COO—; R and R′independently denote —H, —F or a linear or branched alkyl group having1-20 carbon atoms capable of including one methylene group which can bereplaced with —O—, —S—, —CH═CH— or —C≡C—; and m and n are an integer of1-8, with the proviso that R and R′ cannot be —H at the same time when Xand X′ are a single bond.

[0037] In the formula (1), Ar may preferably be a connected ringstructure comprising two fused rings connected with each other via asingle bond, wherein each of said two fused rings comprises 2-5 rings.Further, Ar in the formula (1) may preferably be a connected ringstructure represented by any one of the following formulas (a) to (n):(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)

(k)

(l)

(m)

(n)

[0038] wherein CH is optionally substituted with N or NH, and CH₂ isoptionally substituted with S or O.

[0039] Ar in the formula (1) may preferably be a connected ringstructure represented by the following formula (2):

A—B  (2),

[0040] wherein A and B independently denote any one of phenyl-diyl,pyridine-diyl, pyrazine-diyl, pyrimidine-diyl, pyridazine-diyl,indene-diyl, indolizine-diyl, isoindole-diyl, indole-diyl, purine-diyl,naphthalene-diyl, quinoline-diyl, isoquinoline-diyl, quinoxaline-diyl,1,5-naphthyridine-diyl, 1,6-naphthyridine-diyl, 1,7-naphtharidine-diyl,1,8-naphthyridine-diyl, quinazoline-diyl, cinnoline-diyl,pyrido[2,3-b]pyrazine-diyl, pyrazino[2,3-b]pyrazine-diyl,pteridine-diyl, biphenylene-diyl, fluorene-diyl, carbazole-diyl,thianthrene-diyl, phenalene-diyl, phenanthridine-diyl,phenanthrene-diyl, anthracene-diyl, chrysene-diyl, acridine-diyl,perimidine-diyl, phenanthroline-diyl, phenazine-diyl,phenothiazine-diyl, phenoxathin-diyl, indan-diyl, coumaran-diyl,phthalan-diyl, chroman-diyl, isochroman-diyl, thiachroman-diyl,isothiachroman-diyl, and thiaxanthene-diyl.

[0041] In the formula (2), A may preferably be quinoxaline-diyl.

[0042] In the formula (1) and (2), R═R′, X═X′, m=n=1 are satisfied inthe formula (1), and A=B may preferably be satisfied to form a symmetricstructure having a center of symmetry.

[0043] The organic compounds used for constituting the structural isomermixture in the present invention may desirably be selected based on thefollowing molecular design factors (1) to (3).

[0044] (1) Lowering in LUMO (lowest unoccupied molecular orbital) level

[0045] A electron transport is effected by hopping conduction on LUMO oforganic compound molecules. Accordingly, it is important to improveelectron injection from an electrode to LUMO. Generally, in view ofchemical stability of the electrode, it is difficult to decrease a workfunction of the electrode. As a result, a key feature for the improvedelectron injection is how to lower the LUMO level of organic compoundsused.

[0046] From the above viewpoint, we have calculated HOMO (highestoccupied molecular orbital) levels and LUMO levels of several ringstructures (capable of constituting the organic compounds used in thepresent invention) according to molecular orbital method in order toexpect the LUMO level of the organic compounds. As the molecular orbitalmethod, in the present invention, a semiempirical molecular orbitalmethod (the AM1 method) is used.

[0047] The results are as follows. HOMO LUMO

quinoline −9.2 −0.47

isoquinoline −9.0 −0.56

quinoxaline −9.6 −0.68

[1,5]naphthyridine −9.7 −0.67

[1,6]naphthyridine −9.5 −0.77

[1,7]naphthyridine −9.5 −0.76

[1,8]naphthyridine −9.8 −0.71

quinazoline −9.5 −0.77

pyrido[2,3-b]pyrazine −10.0 −0.93

pyradino[2,3-b]pyrazine −9.9 −1.21

naphtyalene −8.7 −0.27

[0048] As shown above, compared with naphthalene, naphthalene skeletonhaving 1-4 nitrogen atoms (substituted for corresponding CH group(s) ofnaphthalene) can lower the LUMO level of naphthalene.

[0049] Accordingly, by using such heterocyclic fused ring structure as askeleton of organic compound, a resultant electron injection performancefrom an electrode is expected to be improved based on lowering in LUMOlevel.

[0050] (2) Symmetry of molecular structure

[0051] As described in (1), the electroconductivity of liquid crystalcompound is based on the hopping conduction, which varies largelydepending on a magnitude of overlap integral of π electron cloud betweenadjacent molecules. It is important to increase the overlap integral ofthe π electron cloud in order to improve an electron conductivity. Forthe electron conduction, it is effective to impart a(molecular-structural) symmetry to the organic compound molecules so asto dispose their π electron skeletons close to each other, thusincreasing the overlap integral of π electron cloud. As a result, amobility of electron is improved to provide an enhancedelectroconductivity.

[0052] Even if a complete symmetry of molecular structure is notensured, the above advantages are retained as far as organic compoundmolecules have a similar skeleton structure such that both of terminalchains have an almost equal carbon number.

[0053] Accordingly, in the present invention, the organic compounds maypreferably have a symmetric structure having a center of symmetry bydesigning molecular structure so as to satisfy R═R′, X═X′, m=n=1 and A=B(in A-B as Ar) in the above-mentioned formulas (1) and (2).

[0054] (3) Suppression of crystallization in the presence of structuralisomers

[0055] The increase in overlap integral of π electron cloud betweenadjacent molecules leads to an increase in regularity of mutuallyadjacent molecules, thus resulting in a high crystallinity thereof.

[0056] In order to prevent an occurrence of such a crystallization, itis expected that the crystallinity of the structural isomer mixture canbe lowered by mixing a plurality of organic compounds having differentsubstituents outside the π electron clouds, thus providing an amorphousproperty to increase an electroconductivity.

[0057] Accordingly, the structural isomer mixture constituting theelectroconductive layer used in the present invention may desirably beplaced in an amorphous state.

[0058] In the present invention, the above-described three moleculardesign factors (1), (2) and (3) are not necessarily fulfilled at thesame time.

[0059] Based on the above molecular design factors, we have found thatit is possible to realize a luminescence device with a high luminescenceefficiency by using the structural isomer mixture comprising a pluralityof organic compounds of the formula (1) (preferably formula (2)) in acarrier injection and/or transport layer of an organic EL device.

[0060] Particularly, when an electron injection layer is formed by usingthe structural isomer mixture comprising such organic compounds based onthe above molecular design factors, it becomes possible to considerablyimprove an electron injection performance.

[0061] The luminescence device (electroconductive device) with a highluminescence efficiency can be applied to products required to effectenergy saving or provide a high luminance (brightness), such as adisplay apparatus, an illumination apparatus, a light source for aprinter, and a backlight for a liquid crystal display apparatus. Morespecifically, as the display apparatus, it is possible to provide a flatpanel display excellent in energy saving performance, visibility andweight reduction. As the light source for a printer, it is possible toreplace a laser light source of a laser beam printer widely used atpresent with the electroconductive device of the present invention.Image formation may be performed by disposing independently addressabledevices in array and subjecting a photosensitive drum to a desiredexposure to light. By using the electroconductive device of the presentinvention, it is possible to remarkably reduce an apparatus size(volume). With respect to the illumination apparatus and the backlight,it is possible to expect an energy saving performance by the use of theelectroconductive device of the present invention.

[0062] Hereinbelow, specific but non-exhaustive examples of the organiccompounds of the formula (2) constituting the structural isomer mixtureused in the electroconductive device (or EL device) of the presentinvention will be enumerated in the following Tables 5-15. Symbols a₁ toa₃₃ used for specifying a ring structure for liquid crystal compoundsshown in Tables 5-15 have specific skeletons (ring structures) shown inthe following Tables 1-4. TABLE 1 Symbol Name Formula a₁quinoxaline-diyl

a₂

a₃ quinoline-diyl

a₄

a₅ isoquinoline-diyl

a₆

a₇ quinoline-diyl

a₈

[0063] TABLE 2 Symbol Name Formula a₉ [1,5]naphthyridine-diyl

a₁₀ [1,6]naphthyridine-diyl

a₁₁

a₁₂ [1,7]naphthyridine-diyl

a₁₃

a₁₄ [1,8]naphthyridine-diyl

a₁₅ quinazoline-diyl

a₁₆

a₁₇ cinnoline-diyl

[0064] TABLE 3 Symbol Name Formula a₁₈ cinnoline-diyl

a₁₉ pyrido[2,3-b]pyridine-diyl

a₂₀

a₂₁ pyrido[2,3-b]pyrazine-diyl

a₂₂

a₂₃ pyrazino[2,3-b]pyrazine-diyl

a₂₄ pteridine-diyl

a₂₅

[0065] TABLE 4 Symbol Name Formula a₂₆ naphthalene-2,6-diyl

a₂₇ chrycene-2,6-diyl

a₂₈ phenazine-diyl

a₂₉ isochroman-diyl

a₃₀ phenoxathiin-diyl

a₃₁ phenanthroline-diyl

a₃₂ pyrazine-diyl

a₃₃ [1,8]naphthyridine-diyl

[0066] TABLE 5 No. R X A B X′ R′ 1 CH₃ O a₁ a₁ — C₇H₁₅ 2 C₈H₁₇ — a₁ a₁ —C₁₁H₂₃ 3 F — a₁ a₁ — C₂₀H₄₁ 4 H — a₁ a₁ O OC₉H₁₉ 5 C₄H₉ O a₁ a₁ — C₈H₁₇6 C₁₂H₂₅ O a₁ a₁ — C₁₀H₂₁ 7 C₆H₁₃ O a₁ a₁ O C₆H₁₃ 8 C₈H₁₇ O a₁ a₁ OC₈H₁₇ 9 C₁₁H₂₃ O a₁ a₁ O C₁₁H₂₃ 10 C₄H₉OCH(CH₃)CH₂(CH₂)₄ O a₁ a₁ O(CH₂)₄CH₂CH(CH₃)OC₄H₉ 11 C₉H₁₉ O a₁ a₁ O (CH₂)₅OC₃H₇ 12 C₅H₁₁OCH₂₃ O a₁a₁ O (CH₂)₃OC₅H₁₁ 13 C₅H₁₁ O a₁ a₁ O C≡CC₆H₁₃ 14 C₅H₁₁CH═CH O a₁ a₁ OCH═CHC₅H₁₁ 15 C₁₀H₂₁ S a₁ a₁ S C₁₀H₂₁ 16 C₃H₇ — a₁ a₁ — C₃H₇ 17 C₄H₉ —a₁ a₁ — C₄H₉ 18 C₅H₁₁ — a₁ a₁ — C₅H₁₁ 19 C₆H₁₃ — a₁ a₁ — C₆H₁₃ 20 C₇H₁₅— a₁ a₁ — C₇H₁₅

[0067] TABLE 6 No. R X A B X′ R′ 21 C₈H₁₇ — a₁ a₁ — C₈H₁₇ 22 C₉H₁₉ — a₁a₁ — C₉H₁₉ 23 C₁₀H₂₁ — a₁ a₁ — C₁₀H₂₁ 24 C₁₁H₂₃ — a₁ a₁ — C₁₁H₂₃ 25C₁₂H₂₅ — a₁ a₁ — C₁₂H₂₅ 26 C₁₈H₃₇ — a₁ a₁ — C₁₈H₃₇ 27 C₆H₁₃ — a₁ a₁ —C₈H₁₇ 28 C₁₁H₂₃ — a₁ a₁ — C₃H₇ 29 C₆H₁₃ COO a₁ a₁ OOC C₆H₁₃ 30 C₅H₁₁ COOa₁ a₁ COO C₁₁H₂₃ 31 C₂H₅CH(CH₃)CH₂(CH₂)₄ OOC a₁ a₁ COO (CH₂)₅CH(CH₃)C₂H₅32 H — a₁ a₂₆ O C₄H₉ 33 C₈H₁₇ — a₁ a₂₆ O C₅H₁₁ 34 C₁₁H₂₃ — a₁ a₂₆ OC₁₀H₂₁ 35 C₉H₁₉ O a₁ a₂₆ O C₉H₁₉ 36 C₁₅H₃₁ O a₁ a₂₆ O C₇H₁₅ 37 C₁₃H₂₇ —a₁ a₂₆ — C₃H₇ 38 C₆H₁₃ — a₁ a₂₆ — C₆H₁₃ 39 C₉H₁₉ — a₁ a₂₆ — C₉H₁₉ 40C₃H₇ O a₂ a₂ O C₁₄H₂₉

[0068] TABLE 7 No. R X A B X′ R′ 41 C₇H₁₅ — a₂ a₂ — C₇H₁₅ 42 C₁₂H₂₅ — a₂a₂ — C₁₈H₃₇ 43 H — a₂ a₂₆ O C₄H₉ 44 C₈H₁₇ — a₂ a₂₆ — C₁₁H₂₃ 45 C₅H₁₁ —a₂ a₂₆ O (CH₂)₅OC₆H₁₃ 46 C₂H₅ O a₃ a₃ — C₈H₁₇ 47 C₆H₁₃ — a₃ a₃ — C₆H₁₃48 C₇H₁₅ — a₃ a₃ — C₇H₁₅ 49 C₈H₁₇ — a₃ a₃ — C₈H₁₇ 50 C₁₂H₂₅ — a₃ a₃ —C₁₂H₂₅ 51 C₉H₁₉ O a₃ a₃ O C₅H₁₁ 52 C₁₀H₂₁ — a₃ a₂₆ O C₄H₉ 53 C₅H₁₁ — a₃a₂₆ — C₅H₁₁ 54 C₈H₁₇ — a₄ a₄ — C₈H₁₇ 55 C₃H₇ — a₄ a₂₆ O C₁₀H₂₁ 56 C₇H₁₅— a₅ a₅ — C₆H₁₃ 57 C₅H₁₁ O a₅ a₅ — C₅H₁₁ 58 C₃H₇ O a₅ a₅ — C₁₁H₂₃ 59 H —a₅ a₅ O C₁₆H₃₃ 60 C₉H₁₉ O a₅ a₅ O C₇H₁₅

[0069] TABLE 8 No. R X A B X′ R′ 61 C₆H₁₃ — a₅ a₅ — C₆H₁₃ 62 C₇H₁₅ — a₅a₅ — C₇H₁₅ 63 C₈H₁₇ — a₅ a₅ — C₈H₁₇ 64 C₁₃H₂₇ — a₅ a₅ — C₅H₁₁ 65 C₁₀H₂₁— a₅ a₂₆ O (CH₂)₅C≡CCH₃ 66 C₄H₉ — a₅ a₂₆ — C₉H₁₉ 67 C₅H₁₁ — a₅ a₂₆ —C₅H₁₁ 68 C₆H₁₃ — a₆ a₆ — C₆H₁₃ 69 C₁₂H₂₅ — a₆ a₆ — C₁₂H₂₅ 70 C₉H₁₉ — a₆a₂₆ O C₃H₇ 71 C₁₀H₂₁ — a₆ a₂₆ — C₁₀H₂₁ 72 C₃H₇ — a₇ a₇ — C₃H₇ 73 C₁₀H₂₁— a₇ a₇ — C₄H₉ 74 C₁₁H₂₃ — a₇ a₇ O (CH₂)₇CH(CH₃)₂ 75 C₁₇H₃₅ O a₇ a₇ —C₈H₁₇ 76 C₇H₁₅ — a₇ a₇ — C₇H₁₅ 77 C₈H₁₇ — a₇ a₇ — C₈H₁₇ 78 C₉H₁₉ — a₇ a₇— C₉H₁₉ 79 C₁₀H₂₁ — a₇ a₇ — C₁₀H₂₁ 80 C₁₁H₂₃ — a₇ a₇ — C₃H₇

[0070] TABLE 9 No. R X A B X′ R′ 81 C₇H₁₅ — a₇ a₂₆ O CH₃ 82 C₇H₁₅ — a₇a₂₆ OOC C₄H₉ 83 C₈H₁₇ — a₇ a₂₆ — C₈H₁₇ 84 C₇H₁₅ — a₈ a₈ — C₇H₁₅ 85 C₈H₁₇— a₈ a₈ — C₈H₁₇ 86 C₁₂H₂₅ — a₈ a₂₆ O C₅H₁₁ 87 C₁₈H₃₇ — a₈ a₂₆ — C₄H₉ 88C₇H₁₅ — a₉ a₉ — C₇H₁₅ 89 C₈H₁₇ — a₉ a₉ — C₈H₁₇ 90 C₉H₁₉ — a₉ a₉ — C₉H₁₉91 C₄H₉ — a₉ a₉ — C₄H₉ 92 C₁₅H₃₁ — a₉ a₉ — C₁₅H₃₁ 93 C₅H₁₁ — a₉ a₉ —C₈H₁₇ 94 C₁₀H₂₁ — a₉ a₉ — C₆H₁₃ 95 C₆H₁₃ — a₉ a₂₆ COO (CH₂)₃OC₃H₇ 96C₉H₁₉ — a₉ a₂₆ — C₉H₁₉ 97 C₇H₁₅ — a₁₀ a₁₀ O C₆H₁₃ 98 C₇H₁₅ — a₁₀ a₁₀ —C₇H₁₅ 99 C₁₀H₂₁ — a₁₀ a₁₀ — C₁₀H₂₁ 100  C₅H₁₁ — a₁₀ a₂₆ O C₁₁H₂₃

[0071] TABLE 10 No. R X A B X′ R′ 101 C₈H₁₇ — a₁₀ a₂₆ — C₁₂H₂₅ 102 C₈H₁₇— a₁₁ a₁₁ — C₈H₁₇ 103 C₉H₁₉ — a₁₁ a₁₁ — C₉H₁₉ 104 C₃H₇ O a₁₁ a₁₁ — C₈H₁₇105 C₁₈H₃₇ O a₁₁ a₂₆ O C₂H₅ 106 C₆H₁₃ — a₁₂ a₁₂ — C₆H₁₃ 107 C₉H₁₉ — a₁₂a₁₂ — C₉H₁₉ 108 C₁₀H₂₁ — a₁₂ a₁₂ — C₁₀H₂₁ 109 C₁₁H₂₃ — a₁₂ a₁₂ — C₁₁H₂₃110 C₁₂H₂₅ — a₁₂ a₁₂ — C₁₂H₂₅ 111 C₇H₁₅ — a₁₂ a₂₆ O C₅H₁₁ 112 C₁₃H₂₇ —a₁₂ a₂₆ — C₁₀H₂₁ 113 C₄H₉ — a₁₃ a₁₃ — C₄H₉ 114 C₉H₁₉ — a₁₃ a₁₃ S C₈H₁₇115 C₅H₁₁ — a₁₄ a₁₄ — C₅H₁₁ 116 C₇H₁₅ O a₁₄ a₁₄ — C₉H₁₉ 117 C₁₀H₂₁ — a₁₄a₃₃ O (CH₂)₃OC₅H₁₁ 118 C₇H₁₅ — a₁₄ a₃₃ — C₇H₁₅ 119 C₁₂H₂₅ — a₁₄ a₃₃ —C₁₂H₂₅ 120 C₈H₁₇ — a₁₄ a₂₆ — C₄H₉

[0072] TABLE 11 No. R X A B X′ R′ 121 C₆H₁₃ — a₁₄ a₂₆ — C₆H₁₃ 122 C₃H₇ —a₃₃ a₁₄ — C₁₅H₃₁ 123 C₈H₁₇ — a₃₃ a₂₆ O C₈H₁₇ 124 C₃H₇ O a₁₅ a₁₅ — C₁₀H₂₁125 C₇H₁₅ — a₁₅ a₁₅ — C₇H₁₅ 126 C₅H₁₁ — a₁₅ a₁₅ O C₇H₁₅ 127 C₄H₉ — a₁₅a₁₅ — C₄H₉ 128 C₅H₁₁ — a₁₅ a₁₅ — C₅H₁₁ 129 C₆H₁₃ — a₁₅ a₁₅ — C₆H₁₃ 130C₇H₁₅ — a₁₅ a₁₅ — C₇H₁₅ 131 C₈H₁₇ — a₁₅ a₁₅ — C₈H₁₇ 132 C₁₂H₂₅ — a₁₅ a₁₅— C₃H₇ 133 H — a₁₅ a₂₆ O C₁₆H₃₃ 134 C₁₀H₂₁ — a₁₅ a₂₆ — C₁₀H₂₁ 135 C₈H₁₇— a₁₆ a₁₆ — C₈H₁₇ 136 C₁₈H₃₇ — a₁₆ a₁₆ — C₁₈H₃₇ 137 C₆H₁₃ — a₁₆ a₂₆ —C₆H₁₃ 138 C₁₁H₂₃ — a₁₆ a₂₆ O C₂H₅ 139 C₈H₁₇C≡C O a₁₇ a₁₇ — C₁₀H₂₁ 140C₉H₁₉ — a₁₇ a₁₈ O C₃H₇

[0073] TABLE 12 No. R X A B X′ R′ 141 C₇H₁₅ — a₁₇ a₁₇ — C₇H₁₅ 142 C₈H₁₇— a₁₇ a₁₇ — C₈H₁₇ 143 C₉H₁₉ — a₁₇ a₁₇ — C₉H₁₉ 144 C₁₀H₂₁ — a₁₇ a₂₆ —C₁₀H₂₁ 145 C₅H₁₁ — a₁₈ a₁₈ — C₅H₁₁ 146 C₇H₁₅ — a₁₈ a₂₆ O C₁₂H₂₅ 147C₈H₁₇ — a₁₉ a₁₉ — C₈H₁₇ 148 C₄H₉ — a₁₉ a₁₉ — C₄H₉ 149 C₇H₁₅ — a₁₉ a₁₉ —C₇H₁₅ 150 C₁₀H₂₁ — a₁₉ a₁₉ — C₁₀H₂₁ 151 C₈H₁₇ — a₁₉ a₂₆ O C₁₀H₂₁ 152C₇H₁₅ — a₁₉ a₂₆ — C₇H₁₅ 153 C₉H₁₉ — a₂₀ a₂₀ — C₉H₁₉ 154 C₁₂H₂₅ — a₂₀ a₂₀— C₅H₁₁ 155 C₈H₁₇ — a₂₁ a₂₁ — C₈H₁₇ 156 C₆H₁₃ O a₂₁ a₂₁ — C₁₁H₂₃ 157C₁₀H₂₁ — a₂₁ a₂₁ O C₄H₉ 158 C₅H₁₁ — a₂₁ a₂₁ — C₅H₁₁ 159 C₁₁H₂₃ — a₂₁ a₂₁— C₁₁H₂₃ 160 C₄H₉ — a₂₁ a₂₆ O C₁₂H₂₅

[0074] TABLE 13 No. R X A B X′ R′ 161 C₁₉H₃₉ — a₂₁ a₂₆ — H 162 C₁₃H₂₇ —a₂₂ a₂₆ — C₃H₇ 163 C₇H₁₅ — a₂₂ a₂₀ — C₇H₁₅ 164 C₅H₁₁ — a₂₃ a₂₃ — C₅H₁₁165 C₇H₁₅ — a₂₃ a₂₃ — C₇H₁₅ 166 C₁₀H₂₁ — a₂₃ a₂₃ — C₁₀H₂₁ 167 C₄H₉ — a₂₃a₂₃ — C₉H₁₉ 168 C₁₂H₂₅ — a₂₃ a₂₆ O (CH₂)₇CH(CH₃)OC₂H₅ 169 C₃H₇ — a₂₄ a₂₄— C₃H₇ 170 C₆H₁₃ — a₂₄ a₂₄ — C₆H₁₃ 171 C₇H₁₅ — a₂₄ a₂₄ — C₇H₁₅ 172 C₈H₁₇— a₂₄ a₂₄ — C₈H₁₇ 173 C₁₁H₂₃ — a₂₄ a₂₄ — C₁₁H₂₃ 174 C₉H₁₉ — a₂₄ a₂₆ OC₅H₁₁ 175 C₆H₁₃ — a₂₅ a₂₄ — C₄H₉ 176 C₁₇H₃₅ — a₂₅ a₂₅ — C₁₇H₃₅ 177 C₇H₁₅O a₂₇ a₂₇ — C₇H₁₅ 178 C₈H₁₇ — a₂₈ a₂₆ — C₉H₁₉ 179 CH₃ — a₂₉ a₄ — C₁₀H₂₁180 C₉H₁₉ O a₃₀ a₃₀ — C₁₁H₂₃

[0075] TABLE 14 No. R X A B X′ R′ 181 C₄H₉ — a₃₁ a₂₅ — C₁₂H₂₅ 182 C₁₅H₃₁— a₃₂ a₂₆ — C₁₅H₃₁ 183 C₈H₁₇ — a₁ a₄ — C₈H₁₇ 184 C₅H₁₁ — a₁ a₆ — C₅H₁₁185 C₁₂H₂₅ — a₁ a₆ — C₁₂H₂₅ 186 C₇H₁₅ — a₁ a₇ — C₇H₁₅ 187 C₅H₁₁ — a₁ a₈— C₁₁H₂₃ 188 C₉H₁₉ — a₁ a₉ — C₉H₁₉ 189 C₆H₁₃ — a₁ a₁₀ — C₆H₁₃ 190 C₄H₉ —a₁ a₁₄ — C₄H₉ 191 C₇H₁₅ — a₁ a₁₆ — C₇H₁₅ 192 C₁₁H₂₃ — a₁ a₁₈ — C₁₁H₂₃193 C₈H₁₇ — a₁ a₂₅ — C₉H₁₉ 194 C₅H₁₁ — a₃ a₆ — C₅H₁₁ 195 C₁₀H₂₁ — a₇ a₁₀— C₃H₇ 196 C₆H₁₃ — a₇ a₂₂ — C₆H₁₃ 197 C₇H₁₅ — a₁₄ a₁₈ — C₁₀H₂₁ 198 C₄H₉— a₁₅ a₂₅ — C₄H₉ 199 C₆H₁₃ — a₁ a₂₅ — C₅H₁₁ 200 C₈H₁₇ — a₂₄ a₂₆ — C₈H₁₇

[0076] TABLE 15 No. R X A B X′ R′ 201 C₂H₅OC₃H₆ — a₁ a₁ — C₂H₅OC₃H₆ 202C₃H₇OC₃H₆ — a₁ a₁ — C₃H₇OC₃H₆ 203 C₄H₉OC₃H₆ — a₁ a₁ — C₄H₉OC₃H₆ 204(CH₃)₂CHCH₂CH₂CH₂ — a₁ a₁ — CH₂CH₂CH₂CH(CH₃)₂ 205 (CH₃)₂CHCH₂CH₂CH₂CH₂ —a₁ a₁ — CH₂CH₂CH₂CH₂CH(CH₃)₂ 206

— a₁ a₁ —

[0077] In a preferred embodiment, the structural isomer mixture(comprising a plurality of organic compounds) used in the presentinvention may suitably be prepared by reacting two mono-substitutedcyclic compounds (monomers) each having a plurality of reaction sites(positions) with each other or by effecting dimerization of onemono-substituted cyclic compound having a plurality of reaction sites.

[0078] The thus-prepared structural isomer mixture includes a majorcomponent (structural-isomer) and a minor component (structural isomer)in a (major component)/(minor component) ratio of 1/1 to 9/1,particularly 1/1 to 5/1.

[0079] In the electroconductive device of the present invention, theelectroconductive layer comprising the above-mentioned structural isomermixture is disposed between a pair of oppositely disposed electrodes,thus improving current and device characteristics. The electroconductivelayer allows a high joint efficiency with metal and a high (carrier)mobility, so that the resultant electroconductive device is applicableto various semiconductor devices. The structure of the pair ofelectrodes may appropriately be changed depending on characteristics andstructures of the semiconductor devices used.

[0080] In the EL device of the present invention, the electroconductivelayer of structural isomer mixture is used as a carrier injection layerand/or a carrier transport layer, thus improving carrier injectionand/or transport performances from the electrodes to ensure a goodluminescent characteristic.

[0081] The EL device according to the present invention has a principalstructure wherein a luminescence layer and the electroconductive layerof structural isomer mixture (as the carrier injection layer and/or thecarrier transport layer as described above) are disposed between a pairof oppositely disposed electrodes as shown in FIGS. 6 and 7.

[0082] Referring to FIGS. 6 and 7, materials for the transparentsubstrate 21, anode (transparent electrode) 22, luminescence layer 24and cathode (metal electrode) 25 may be known ones.

[0083] More specifically, the anode 22 may be formed of a transparentconductive material having a larger work function, preferably ITO(indium tin oxide) or IZO (indium zinc oxide). ITO may preferablycontain 1-30 wt. % of SnO₂ per In₂O₃, and IZO may preferably contain5-30 wt. % of ZnO per In₂O₃, so as to provide a lower electricresistance. The anode 22 may also be formed of other materials, such asindium oxide, tin oxide, Cd₂SnO₄, zinc oxide, copper iodide, gold andplatinum.

[0084] The cathode 25 may be formed of a material (metal, alloy orcompound) having a smaller work function by (vacuum) vapor deposition orsputtering. Examples of the material for the cathode 25 may include imetals, such as K, Li, Na, Mg, Ka, Ce, Ca, Cr and Ba; compounds, such asBaO, BaS, CaO, HfC, LaB₆ MgO, MoC, NbC, PbS and SiO; and alloys of Al—Ca(Ca=1-30 wt. %) and Al—Li (Li=0.5-10 wt. %), in order to improvestability.

[0085] The luminescence layer 24 may be formed of Alq 3(tris(8-quinolinato)aluminum), BeBq (bis(benzoquinolinolato)berylliumcomplex), DTVBi (4,4′-bis-(2,2-di-p-tolyl-vinyl)-biphenyl), Eu (DBM)₃(Phen) (tris(1,3-diphenyl-1,3-propanediono) (mono-phenanthroline) Eu(III), diphenylethylene derivatives, triphenylamine derivatives,diaminocarbazole derivatives, bisstyryl derivatives, benzothiazolederivatives, benzoxazole derivatives, aromatic diamine derivatives,quinacridone compounds, perylene compounds, oxadiazole compounds,coumarin compounds, and anthraquinone compounds. These materials maypreferably be formed in a layer in an amorphous state by vacuum (vapor)deposition.

[0086] The electroconductive layer formed of the above-mentionedstructural isomer mixture is used as at least one layer of a holetransfer layer 23 (shown in FIGS. 6 and 7), an electron transport layer31 (shown in FIGS. 6 and 7), a hole injection layer (not shown) and anelectron injection layer (not shown). These carrier injection andtransport layers other than the electroconductive layer may be formed ofknown materials.

[0087] In the EL device of the present invention, the electroconductivelayer of structural isomer mixture may particularly preferably be usedas the electron injection layer. More specifically, in an ordinary ELdevice, it is generally difficult to effect injection of electrons fromthe cathode into the organic compound layer(s) compared with injectionof holes from the anode into the organic compound layer(s). This may beattributable to difficulty of decreasing a work function of a metal(used for the metal (cathode) electrode) compared with LUMO level of theorganic material used, due to lower stability of the metal material.Accordingly, in the EL device having such a structure that one or pluralorganic compound layers (films) are disposed between the cathode and theanode, the electroconductive layer of structural isomer mixture mayeffectively used as the electron injection layer, thus allowing use of amaterial having a molecular structure with a high planarity (whichcannot be conventionally used due to crystallization of its depositedfilm) to give more latitude in selection of material used.

[0088] The hole transport layer may be formed of an electron-donatingmaterial, such as triphenyldiamine derivatives (a representative examplethereof may include α-NPD (bis[N-(1-naphthyl)-N-phenyl]benzidine) shownhereinafter). Examples of the hole injection layer material may includetetraarylbenzidine compounds (triphenyldiamine), hydrazone derivatives,carbazole derivatives, triazole derivatives, imidazole derivatives,oxadiazole derivatives and polythiophene.

[0089] In the case of forming the electron injection layer, a materialtherefor may include quinoline derivatives (such as Alq3 describedabove), oxadiazole derivatives and perylene derivatives.

[0090] Hereinbelow, the present invention will be described morespecifically based on Examples.

EXAMPLE 1

[0091] (Synthesis of Ex. Comp. No. 19)

[0092] In a 2 liter-round bottomed flask, 64 g (371.1 mM) of1,2-diamino-4-hexylbenzene (a) and 49.5 g (412.1 mM) of1,4-dioxane-2,3-diol (b) were placed and dissolved in 793 ml of ethanol,followed by stirring overnight at room temperature.

[0093] After the reaction, the reaction mixture was subjected todistilling-off of the solvent under reduced pressure and purified bysilica gel column chromatography (eluent: toluene/ethyl acetate=1/4),followed by distilling-off of the solvent under reduced pressure toobtain 53.3 g of 6-hexyl-quinoxaline (e).

[0094] In a 200 ml-round bottomed flask, 53.3 g (248.7 mM) of6-hexylquinoxaline (c), 31 g (258.8 mM) of pyridine-1-oxide and 20 g ofpalladium-carbon were placed and heat-refluxing overnight understirring. After cooling, the reaction mixture was subjected tofiltration, followed by distilling-off of the solvent under reducedpressure to obtain a residue. The residue was washed with ethanol andsubjected to filtration, followed by recrystallization from pyridine toobtain a crude product. The crude product was dissolved in chloroformand filtered with alumina. The filtrate was recrystallized from tolueneto obtain 10.4 g of structural isomer mixture (2,2′-bihexyl-quinoxaline((d1)/(d2)/(d3)=1/2/1); Ex. Comp. No. 19).

[0095] The structural isomer mixture showed the following phasetransition series.

[0096] Phase transition temperatures (°C.)${Crystal}\quad \underset{\quad 134.4\quad}{\overset{\quad 154.5\quad}{\rightleftharpoons}}\quad {{Isotropic}\quad {phase}}$

[0097] The above-prepared structural isomer mixture (Ex. Comp. No. 19)and two comparative compounds (Comparative Compounds 1 and 2) wereevaluated in terms of crystallization characteristic in the followingmanner.

[0098] Each compound was formed in a 20 nm-thick film by vacuum (vapor)deposition and observed at 30° C., thus determining a time required tocause crystallization.

[0099] The results are shown in Table 16. TABLE 16 Ex. CrystallizationComp. No. Formula (Hr at 30° C.)

19

>72

Comparative compound 1

12 Comparative compound 2

0

[0100] As shown in Table 16, compared with monomolecular compounds(Comparative Compounds 1 and 2), the structural isomer mixture (Ex.Comp. No. 19) provided a stable amorphous structure.

EXAMPLE 2

[0101] An organic EL device (electroconductive device) having asectional structure as shown in FIG. 1 was prepared by using thestructural isomer mixture (Ex. Comp. No. 19) prepared in Example 1 inthe following manner.

[0102] On a 1 mm-thick glass substrate 11, a 70 nm-thick ITO (indium tinoxide) film was formed as an anode (ITO electrode) 12 by sputtering andultraviolet-light irradiation for surface treatment (cleaning).

[0103] The above-treated substrate 11 having the ITO film (anode) 12 wasplaced in a vacuum chamber held at a pressure of ca. 1.33×10⁻³ Pa (ca.1×10⁻⁵ Torr), and a 50 nm-thick layer of α-NPD(bis[N-(1-naphthyl)-N-phenyl]benzidine) represented by a formula shownbelow was formed on the ITO film 12 as a hole (carrier) transportinglayer 13 by (resistance heating) vacuum deposition at a rate of 0.1nm/sec.

three organic layer segments (luminescence layer segments) 14 exhibitingdifferent luminescent wavelengths were respectively formed in athickness of 50 nm on the hole transporting layer 13 by vacuumdeposition. The three organic layer (luminescence layers) 14 a-14 c wererespectively formed of (95 wt. % of) Alq3 of a formula (a) shown belowdoped with 5 wt. % of perylene of a formula (b) shown below for shiftingthe luminescence wavelength to a shorter wavelength side, (95 wt. % of)Alq3 of the formula (a) doped with 5 wt. % of DCM (a styryl dye) of aformula (c) shown below for shifting the luminescence wavelength to alonger wavelength side, and Alq3 alone (providing a center luminescencewavelength).

[0104] On each of the luminescence layers 14 a-14 c, a 20 nm-thick layerof a structural isomer mixture (Ex. Comp. No. 19) was formed as anelectron (carrier) injection layer 16 by vacuum deposition.

[0105] The thus-formed electron injection layer (structural isomermixture layer) 16 was coated with a lamination-type cathode metal layeras a cathode electrode 15 each comprising a 10 nm-thick layer of Al—Lialloy (Al/Li=98.2/1.8 by weight) and a 150 nm-thick Al layer,respectively, formed by vacuum deposition to prepare an organic ELdevice as shown in FIG. 1.

[0106] The thus-prepared EL device was subjected to measurement of acurrent-voltage characteristic and a luminescence efficiency at roomtemperature at a portion containing the luminescence layer 14 ccomprising Alq3 alone (i.e., free from the dopants of the formulas (b)and (c)) by using a microammeter (“4140B”, mfd. by Hewlett-Packard Co.)and a luminance meter (“BM7”, mfd. by Topcon K.K.), respectively.

[0107] The results are shown in FIGS. 2 and 4, respectively.

[0108] Referring to FIG. 2, the resultant current-voltage curve showedthat the EL device provided a good rectifying performance and a highercurrent density with respect to an applied electric field. Further, asshown in FIG. 4, it was also confirmed that the EL device provided ahigher luminescence efficiency in proportion to the current density.

[0109] The higher current density may be attributable to improvement inelectron injection efficiency (performance) by the use of the structuralisomer mixture (Ex. Comp. No. 19 in this example) since the EL deviceprovided the higher current density compared with that in ComparativeExample 1 below although the EL device had a lower electric fieldintensity.

COMPARATIVE EXAMPLE 1

[0110] An organic EL device was prepared and evaluated in the samemanner as in Example 2 except that the electron injection layer 16 (ofthe structural isomer mixture (Ex. Comp. No. 19) was not formed.

[0111] The results (current-voltage characteristic and luminescenceefficiency are shown in FIGS. 3 and 5, respectively.

[0112] Compared with FIG. 2 (Example 2), although a higher electricfield strength (a smaller organic compound layer thickness) was applied,the EL device (of Comparative Example 1) provided smaller currentdensity values as shown in FIG. 3, thus resulting in an inferiorelectron injection performance.

[0113] As described hereinabove, according to the present invention, byusing the electroconductive layer formed of structural isomer mixtureexcellent in carrier injection and/or transport characteristics, it ispossible to apply the resultant electroconductive device to variousdevices including semiconductor devices, thus improving theircharacteristics. Particularly, the organic EL device according to thepresent invention wherein the electroconductive layer is used as acarrier injection layer and/or a carrier transport layer providesimproved luminescence efficiency and current-voltage characteristic, sothat it is also possible to employ a thicker organic compound layerthereby to improve a reliability (e.g., prevention of occurrence ofshort-circuit between a pair of electrodes).

What is claimed is:
 1. An electroconductive device, comprising: a pairof oppositely disposed electrodes, and a luminescence layer and anelectroconductive layer disposed between the electrodes, wherein theelectroconductive layer comprises a mixture of a plurality of organiccompounds which are mutually structural isomers and include a majorcomponent and a minor component, the mixture comprising the major andminor components in a (major component)/(minor component) ratio of 1/1to 9/1.
 2. A device according to claim 1, wherein the organic compoundsare represented by the following formula (1):(R—X)_(n)—Ar—(X′—R′)_(m)  (1), wherein Ar denotes a connected ringstructure comprising two single rings connected with each other via asingle bond or two fused rings connected with each other via a singlebond; X and X′ independently denote a single bond, —O—, —S—, —OOC— or—COO—; R and R′ independently denote —H, —F or a linear or branchedalkyl group having 1-20 carbon atoms capable of including one methylenegroup which can be replaced with —O—, —S—, —CH═CH— or —C≡C—; and m and nare an integer of 1-8, with the proviso that R and R′ cannot be —H atthe same time when X and X′ are a single bond.
 3. A device according toclaim 1, wherein Ar in the formula (1) is a connected ring structurecomprising two fused rings connected with each other via a single bond,each of said two fused rings comprising 2-5 rings.
 4. A device accordingto claim 2, wherein Ar in the formula (1) is a connected ring structurerepresented by any one of the following formulas (a) to (n):

wherein CH is optionally substituted with N or NH, and CH₂ is optionallysubstituted with S or O.
 5. A device according to claim 2, wherein Ar inthe formula (1) is a connected ring structure represented by thefollowing formula (2): A—B  (2), wherein A and B independently denoteany one of phenyl-diyl, pyridine-diyl, pyrazine-diyl, pyrimidine-diyl,pyridazine-diyl, indene-diyl, indolizine-diyl, isoindole-diyl,indole-diyl, purine-diyl, naphthalene-diyl, quinoline-diyl,isoquinoline-diyl, quinoxaline-diyl, 1,5-naphthyridine-diyl,1,6-naphthyridine-diyl, 1,7-naphtharidine-diyl, 1,8-naphthyridine-diyl,quinazoline-diyl, cinnoline-diyl, pyrido[2,3-b]pyrazine-diyl,pyrazino[2,3-b]pyrazine-diyl, pteridine-diyl, biphenylene-diyl,fluorene-diyl, carbazole-diyl, thianthrene-diyl, phenalene-diyl,phenanthridine-diyl, phenanthrene-diyl, anthracene-diyl, chrysene-diyl,acridine-diyl, perimidine-diyl, phenanthroline-diyl, phenazine-diyl,phenothiazine-diyl, phenoxathin-diyl, indan-diyl, coumaran-diyl,phthalan-diyl, chroman-diyl, isochroman-diyl, thiachroman-diyl,isothiachroman-diyl, and thiaxanthene-diyl.
 6. A device according toclaim 5, wherein A in the formula (2) is quinoxaline-diyl.
 7. A deviceaccording to claim 5, wherein R═R′, X═X7 and m=n=1 are satisfied in theformula (1), and A=B is satisfied in the formula (2) to form a symmetricstructure having a center of symmetry.
 8. A device according to claim 1,wherein the mixture of a plurality of organic compounds is in anamorphous state.
 9. An electroluminescence device, comprising: a pair ofoppositely disposed electrodes, and a luminescence layer and a carrierinjection layer and/or a carrier transport layer disposed between theelectrodes, wherein the carrier injection layer and/or the carriertransport layer comprises the electroconductive layer of theelectroconductive device according to claim
 1. 10. A device according toclaim 9, wherein the device comprises the luminescence layer and thecarrier injection layer disposed between the electrodes, the carrierinjection layer being an electron injection layer.
 11. A process forproducing an electroconductive device of the type comprising a pair ofoppositely disposed electrodes and an electroconductive layer disposedbetween the electrodes, said process comprising: a step of forming anelectroconductive layer comprising a mixture of a plurality of organiccompounds between the electrodes, the organic compounds being mutuallystructural isomers and including a major component and a minorcomponent; wherein the mixture comprises the major and minor componentsin a (major component)/(minor component) ratio of 1/1 to 9/1.
 12. Aprocess according to claim 11, wherein the electroconductive layer isformed through vacuum deposition.